how would I do that?
Programming a game (2D, 3D or otherwise) in D3D11 is a bit more than can be (or should be) explained in a topic. Googling for tutorials or game engines which implement 2D using D3D11 would be a good place to start.
Would I simply map textures onto primitives and fix the camera(view/projection)?
Pretty much. Most 2D games use a single angle of view and (commonly) an orthographic projection. As mentioned, you'll have to decide if you're coding for a side-scroller, a top-down, a 3/4 view, etc., before you start. Getting some experience with 2D rendering in a scratch project will benefit you a lot.
What about a "hybrid model" where it's the same as the above but somehow to take advantage of 3D models
As mentioned, you can use 3d models for your animated characters, but animating/rendering may be simpler and more efficient with images of various character orientations, versus modeling various poses or animations for a 3d model. True, you wouldn't have to re-capture images if you modify your 3d models, but you'll have to decide if your game is for your convenience while you create it or for the end product.